user
Generate a theory of why a given phenomenon happens.

Now complete the following instance -
Input: Lunar eclipse
Output:
assistant
A lunar eclipse occurs when the Earth passes directly between the Sun and the Moon, casting a shadow on the Moon and temporarily blocking the Sun's light from reaching the Moon's surface. This happens because the Earth's orbit is slightly tilted from the Sun's orbit, allowing the three celestial bodies to align in a straight line. The Moon's orbit around the Earth is slightly elliptical and its orbit shifts, resulting in either a partial lunar eclipse or a total lunar eclipse.